Gray cards and other calibration and reference cards and tools are often used in photography to adjust the settings of a camera to compensate for ambient or studio lighting conditions. For example, using a gray card, the photographer places the gray card in the vicinity of the photographic subject, thereafter taking a reading with a light meter (being either stand-alone or integral to the camera), and adjusts the settings such as the shutter speed and aperture size to obtain the proper exposure for that particular lighting condition.
Although the term “gray card” is often used, describing the common color of the card, these reference cards can be created with various colors, such as black, white, or gray, as well as various surface textures and reflective characteristics. Often, the gray colored card, usually 18% gray, is used to determine the proper exposure settings for a given photographic subject lighting condition. A white colored card can be used to adjust the color or white balance. Black and various shades of colors, such as the colors found in the GretagMacbeth ColorChecker Chart can be used for various adjustments, both during the photographic process and during development or digital processing.
These existing cards come in a variety of materials and sizes. They could be made of cloth, cardboard, plastic, and the like, with at least one surface coated with a reference color or material. More often than not, the materials should be matt in finish, to reduce glare. The size of the card could vary, including 8″×10″, 2″×3.5″, and so on.
The common problem with all existing gray cards, is that they are an accessory to the camera, either being attached by a lanyard or carried separately. Photographers, have a need to carry many pieces of equipment beyond the camera itself, including various lenses, film, flash memory, tools, and so on. The gray card is one more item to pack and carry around. Basically, they can be bulky and inconvenient to carry at all times, especially for the photographer that is traveling light.
Some current technologies to calibrate white balance include a filter on a lens cap. The lens cap is left on the lens during the calibration process. The light enters through the filter of the lens cap, being read by an in-lens digital sensor. Instead of relying on reflected light from a gray card near the photographic subject, it relies on filtered light for white balance, allowing through the filter a specific wavelength of visible light.
What is needed and heretofore not provided is a reference surface, such as an 18% gray surface, that is compact. What is also needed is a reference surface that is an integral part of the equipment necessary to photography. Additionally, what is needed is a reference surface that is easy to use and instantly available at all times during the photographic process.